Lighting control apparatus for vehicle lamp

Abstract

When the level at an input terminal goes low upon the reception of a signal to dim an LED, a PNP transistor is rendered on and a voltage at the positive input terminal of an operational amplifier is raised, in accordance with a time constant that is defined by a resistor and a capacitor. In accordance with the increase in this voltage, a source current is supplied from the operational amplifier to a current detection terminal, and as the value of the source current is gradually increased, a current flowing across the shunt resistor of the switching regulator is gradually reduced. Further, the light emission level of the LED is gradually lowered from the fully lighted state to the 70% lighted state, and there is, for the LED, a light quantity change of about 30% in ten seconds.

Description

[0001]The present application claims foreign priority based on Japanese Patent Application No. P.2005-222624, filed on Aug. 1, 2005, the contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a lighting control apparatus for vehicle lamp, and relates particularly to a lighting control apparatus, for vehicle lamp, that controls the lighting of a semiconductor light source constituted by a semiconductor light emitting device.[0004]2. Related Art[0005]Conventionally, a halogen lamp or a discharge lamp is employed as a lighting source for vehicle lamps. If the light quantity is changed, the service life of a light source of this type may be greatly reduced, or the maintenance of a long lighting period may not be possible. Therefore, since the light is on by supplying a consistent amount of power, such as 55 W or 35 W, a consistent amount of power always is consumed.[0006]On the other hand, w...

AI Technical Summary

Benefits of technology

The solution ensures comfortable and safe driving by gradually adjusting LED light output to match luminous intensity standards, while reducing energy consumption, and allows immediate recovery of light levels when high beam is switched off, thus enhancing driving safety and energy efficiency.

Problems solved by technology

If the light quantity is changed, the service life of a light source of this type may be greatly reduced, or the maintenance of a long lighting period may not be possible.

However, when a semiconductor light source is dimmed, this is accompanied with a drastic change in the light quantity, even though power can be saved.

Therefore, a driver may feel unconformable and partially blinded, and this will degrade driving safety.

Images